[PATCH 4/6] slab: move validate_slab_ptr() from alloc_consistency_checks() to its caller

Vlastimil Babka
2025-09-11T17:02:41Z

In alloc_debug_processing() we can call validate_slab_ptr() upfront and
then don't need to recheck when alloc_consistency_checks() fails for
other reasons.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/slub.c | 30 ++++++++++++++----------------
1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 94a089205a86f0667444484e158d307e72cd96e1..909c71372a2f542b6e0d67c12ea683133b246b66 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1633,11 +1633,6 @@ void setup_slab_debug(struct kmem_cache *s, struct slab *slab, void *addr)
static inline int alloc_consistency_checks(struct kmem_cache *s,
struct slab *slab, void *object)
{
- if (!validate_slab_ptr(slab)) {
- slab_err(s, slab, "Not a valid slab page");
- return 0;
- }
-
if (!check_slab(s, slab))
return 0;

@@ -1656,6 +1651,11 @@ static noinline bool alloc_debug_processing(struct kmem_cache *s,
struct slab *slab, void *object, int orig_size)
{
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
+ if (!validate_slab_ptr(slab)) {
+ slab_err(s, slab, "Not a valid slab page");
+ return false;
+ }
+
if (!alloc_consistency_checks(s, slab, object))
goto bad;
}
@@ -1667,17 +1667,15 @@ static noinline bool alloc_debug_processing(struct kmem_cache *s,
return true;

bad:
- if (validate_slab_ptr(slab)) {
- /*
- * If this is a slab page then lets do the best we can
- * to avoid issues in the future. Marking all objects
- * as used avoids touching the remaining objects.
- */
- slab_fix(s, "Marking all objects used");
- slab->inuse = slab->objects;
- slab->freelist = NULL;
- slab->frozen = 1; /* mark consistency-failed slab as frozen */
- }
+ /*
+ * Let's do the best we can to avoid issues in the future. Marking all
+ * objects as used avoids touching the remaining objects.
+ */
+ slab_fix(s, "Marking all objects used");
+ slab->inuse = slab->objects;
+ slab->freelist = NULL;
+ slab->frozen = 1; /* mark consistency-failed slab as frozen */
+
return false;
}

--
2.51.0